TCR Sole Proprietorship Campaign Option
TCR has an option for submissions to be a Sole Proprietorship with an individual's social security number instead of requiring an EIN and registered company. The campaigns have a lower messaging volume (capped at 1.000 messages), but TCR does have a path for them to get texting approval. For some reason, RingCentral does not provide this option to customers despite selling to many franchisees and sole proprietorships for phone service with the reasonable expectation that they can also text with the service since it's advertised all over the site (and by their sellers) as included with the seat(s).
Twillio, OpenPhone, and other small providers offer this option to their customers as do some other texting only services.